The objective of this proposed study is to obtain measurements of pressure pulse wave characteristics, velocity waveforms and profiles, and wall shear stresses at various sites in the coronary circulation of large animals. As an example, coronary arteries in the horse may reach 1 cm or more in diameter. In this species the vessels thus are large enough to permit measuring flow properties with greater resolution, at bifurcations, and at smaller tributaries. Particular emphasis will be placed on the measurement of wall shear stress and velocity waveforms using hot-film anemometry and on the effects of drugs and various simulated cardiac abnormalities. These measurements will be analyzed with particular emphasis on the effects of geometry, Reynolds number, and the unsteadiness parameter. These studies, in addition to permitting measurement with increased resolution, are designed to extend the range of measurements in vivo to animals larger than man. They are believed to have significance to the understanding of the hemodynamic factors in arterial disease.